Say the ratio out loud before you open Reasoning — recalling it unprompted is exactly what the exam pays for.
Why it matters
A foreign judgment is not enforced because a foreign court said so. Something in the forum's own law must convert it into a domestic right. The older answer was comity; the modern answer is the doctrine of obligation, and Baron Parke's sentence in Williams v. Jones is where the modern answer is stated.
This is the theory question of the module, and it is worth more than it looks, because the doctrine of obligation explains the structure of the law that follows: why a foreign judgment can be sued on as a debt, why the burden shifts to the defendant once it is proved, and why the defences are the shape they are.
Facts
The course states the case for the principle and not for a narrative. Treat it as a statement of the basis of enforcement, and do not attribute facts to it in an answer.
Held
Baron Parke's formulation:
"where a court of competent jurisdiction has adjudicated a certain sum of money to be due from one person to another, a legal obligation arises to pay that sum on which an action of debt to enforce the judgment may be maintained- thus the judgments of foreign and colonial courts are supported and enforced".
Once the foreign judgment is proved, the burden shifts to the defendant to show why he should not perform.
Reasoning
Step one: identify what the foreign judgment creates. Not a command that binds the forum, but an obligation owed by the judgment debtor. The obligation is a species of debt, and debts are enforced by the ordinary domestic action.
Step two: attach a condition to it. The obligation arises only where the adjudicating court was of competent jurisdiction — competence in the international sense, on Sirdar Gurdyal Singh. And the sum must be a definite one: "The obligation to pay under a foreign judgment can arise only in the case of a definite sum", which is why in Sadler v. Robins a Jamaican decree ordering payment after deducting costs still to be taxed supported no action.
Step three: shift the burden. The judgment creditor proves the judgment; from there the defendant must show a ground for not performing.
Step four: derive the defences from the obligation itself. "Existence of an obligation being the basis of liability, any ground which negatives the obligation can be pleaded in defense." That is the doctrinal link to the Indian scheme: the six clauses of s. 13 of the Code are precisely a list of grounds that negative the obligation.
Why comity was abandoned. Comity "is an inadequate basis, an uncertain ground and gives rises to difficulties", because it makes enforcement turn on reciprocity; and if reciprocity is the criterion it would leave no "Scope for any defense against those judgments except possibly the want of jurisdiction", which "is obviously against the elementary notions of justice." The obligation theory has two advantages in exactly those places. First, reciprocity is eliminated: an obligation once recognised must be enforced irrespective of how the forum's own judgments are treated abroad. Second, the defences become principled rather than discretionary.
Exam use
It opens: What is the basis of enforcement of foreign judgments? — set out comity, give the critique, then Williams v. Jones, then the two advantages, then s. 13 of the Code as the statutory expression of the defences.
Pair it with Godard v. Gray on conclusiveness. The obligation theory made the older view — that a foreign judgment was mere evidence, re-examinable on the merits — untenable, and Godard v. Gray killed it: a French court's misconstruction of an English penalty clause was no defence, because "there can be no difference between a mistake as to English law and any other mistake."
Mention the anomaly it left behind. The rule against merger survives: a creditor holding a foreign judgment "may either sue B in England on the foreign judgment or he may bring an action against B in England on the debt in which case the foreign judgment can be used only as evidence of the debt." The rationale for that rule died with Godard v. Gray, and Lord Wilberforce in Carl Zeiss v. Rayner & Keeler called the survival an "illogical survival" whose continued existence was "precarious".
It does not decide: which courts are competent — that is Gurdyal Singh; nor what defeats the obligation — that is the list of defences, fraud, public policy and natural justice, and s. 13 in India; nor anything about judgments that are only recognised and never enforced, such as a foreign decree of divorce or of nullity, where the obligation theory has no work to do because there is no sum to pay.